Hi Kevin,
Thanks for your detailed explanation.
I notice that you encounter two issues when using list in SharePoint classical experience and for now you have provided enough information about “a user fills out a form and enters information into the 6-line text box, the line scrolls to the right instead of wrapping to the next line”.
For further investigation, could you also provide the detailed step and related screenshots about “the "Multiple lines of text" box only shows one line and you cannot see beyond the right border of the box” to us by PM?
Your effort is high appreciated.
Regards,
Spike